Climate change and coastal erosion

Gareth Jenkins from the British Geological Survey describes the effects of climate change on coastal erosion and landslides on the Aldbrough coast. He describes some of the monitoring work BGS are doing in the area using terrestrial LiDAR surveys.

The eroding coastline of the Holderness area. Coastal erosion occurs when the sea wears away the land. A great deal of coastal erosion has taken place in the Holderness area on the east coast of England. Erosion is so dramatic here because the cliffs along the coast are made from soft till, which is soft and crumbly rock. Heavy rains and storm surges make the erosion occur more rapidly.

Climate change forecasts predict an increase in global temperatures; over the past 25 years an increase of 0.2°C per decade has been observed*.

This is likely to cause global sea levels to rise yet further — they are currently rising around 3 mm per year* — and an increase in the frequency and magnitude of storm events.

When these two factors are combined it will have the effect of focusing wave energy closer to the shore and cliff faces, leading to increased rates of coastal erosion in areas where cliffs are composed of soft rocks.

'Storm surge'

Another factor associated with storm events is ‘storm surge’. Extreme low pressure over an area can cause sea level to rise locally, which can lead to coastal flooding in low-lying areas, and overtopping of sea defences.

At Aldbrough, on the Holderness coast in North Yorkshire, the cliffs are made of soft till, a mixture of clay, silt, sand, gravel, cobbles and boulders deposited by a glacier.

These cliffs are being actively eroded by wave attack at the base. Erosion rates are estimated to be around 1.5 metres per year.

Wave erosion at the base removes the support for the upper section of the cliff. This causes the cliff to become unstable and fail, most commonly as a rotational
landslide.